Advancing Food Packaging: Exploring Cyto-Toxicity of Shape Memory Polyurethanes.

Area of Science:

• Materials Science
• Biomaterials Engineering
• Polymer Chemistry

Background:

• Cytotoxicity is crucial for materials in biological applications like food packaging.
• Shape-memory polyurethanes (SMPUs) offer versatile properties but their use of aromatic isocyanates (MDI, TDI) poses risks due to potential carcinogenic degradation products.

Purpose of the Study:

• To evaluate the impact of different isocyanates (aromatic vs. aliphatic) and polyol chain length on the cytotoxicity of synthesized SMPUs.
• To assess SMPU cytotoxicity before and after light-induced degradation.

Main Methods:

• Synthesis of SMPUs using poly(tetramethylene ether) glycol (PTMG) and castor oil (CO) with four isocyanates: MDI, TDI, HDI, and IPDI.
• Cytotoxicity assays to measure cell proliferation rates.
• Assessment of polyol chain length influence using PTMG with varying molecular weights (1000, 650, 250 g·mol⁻¹).
• Characterization of thermal and mechanical properties (TGA, DSC, DMA, TMA).

Main Results:

• All SMPUs showed >90% cell proliferation before degradation.
• After degradation, aromatic isocyanate-based SMPUs had <10% cell proliferation, while aliphatic isocyanate-based SMPUs maintained >70%.
• Longer PTMG chain lengths correlated with higher cell proliferation rates both before and after degradation.

Conclusions:

• Aliphatic isocyanates are preferable to aromatic isocyanates for synthesizing SMPUs intended for biological applications due to significantly lower post-degradation cytotoxicity.
• Longer polyol chain lengths enhance the cytocompatibility of SMPUs.
• These findings are critical for developing safer shape-memory polyurethane biomaterials.